1. Field of the Invention
The present invention relates to a Zero Insertion Force (ZIF) socket, and particularly to a ZIF socket having an improved cam mechanism for driving a cover to slide on a base of the ZIF socket.
2. Description of Prior Art
ZIF sockets are known in the art for connecting Integrated Circuit (IC) packages to printed circuit boards. Referring to FIGS. 6 and 7, a conventional ZIF socket 6 usually employs a cam mechanism 9 to drive a cover 8 to slide on a base 7 in a front-to-back direction. The cam mechanism 9 comprises a base ring 92 and a cam device 91 which is composed of four column-shaped portions. A riveting portion 93 is formed at a bottom end of the cam device 91 for being riveted on the base ring 92, thereby securing the cam device 91 in the cover 8 and the base 7. However, because the base ring 92 directly abuts against a bottom face 71 of the base 7, the necessary force exerted on the cam mechanism 9 for driving the cam device 91 to rotate in a corresponding hole of the base 7 is greatly increased.
Hence, a ZIF socket having an improved cam mechanism is required to overcome the disadvantages of the prior art.
The object of the present invention is to provide a ZIF socket with a cam mechanism which has five column-shaped portions and forms a supporting surface therewith for reducing a torque to be exerted on the cam mechanism.
In order to achieve the above-mentioned object, a ZIF socket in accordance with the present invention includes a dielectric base, a cover slidably mounted on the base, a plurality of contacts received in the base, and a cam mechanism engaged with the cover and the base. The cam mechanism comprises a cam device and a base ring attached to the cam device from a bottom side thereof. The cam device is composed of five column-shaped portions, the diameters of which are degressive from the uppermost one to the lowermost one. A first driving portion and a second driving portion of the cam device are received in corresponding first and second holes of the cover. A first rotating portion extending straightly and downwardly from the second driving portion and a second rotating portion are both retained in an elliptic hole defined in the base. A riveting portion projects downwardly from the second rotating portion and engages with the base ring and is then subject to a riveting operation. A topside of the base ring abuts directly against a supporting surface formed on a lower end of the second rotating portion of the cam device instead of abutting against a bottom face of the conventional ZIF socket thus to reduce the torsion force required to rotate the cam mechanism.
Other objects, advantages and novel features of the invention will become more apparent from the following detailed description of the present embodiment when taken in conjunction with the accompanying drawings.